Basswood Lace Bug – Gargaphia tilia
Basswood Lace Bug: Appearance, Territory, Damage, and Life Cycle
Latin Name: Gargaphia Tiliae
Appearance: Adults range in length from 1/8 to 1/3 inch. Body-color is light with black markings. The wings are maintained flat and extend beyond the abdomen. The tops of their wings and thorax are sculptured and lacey. The nymphs lack wings. They have a spiny body with a flat oval form and are darker than adults. Lace bug nymphs molt their exoskeletons, but their cast skins remain connected to the plant’s leaf. Adults and nymphs leave tiny, black droppings on the undersides of leaves.
Hosts Plants: Lace bugs are more common on plants that receive full sunlight, such as rhododendron and azalea than on plants that receive partial shade.
Territory: Eastern Europe and the USA
Damage Insect Cause: Adults and nymphs eat on the underside of leaves with needle-like mouthparts inserted into leaf tissue. This results in tiny, mottled white or yellow dots on the top leaf surface. Feeding damage is most visible in the middle to late summer when populations are at their peak. Leaf discoloration and early leaf loss might result from overfeeding. Lace bugs may cause harm to healthy, mature trees and plants. Plant development in fresh transplants can be inhibited if feeding occurs for multiple years in succession. Lace bug populations and damage severity fluctuate from year to year.
Lace bug management is often unnecessary since lace bugs are vulnerable to a variety of natural enemies, including predators such as green lacewings, plant bugs, assassin bugs, minute pirate bugs, and spiders. Lace bugs may be readily dislodged from plants with a strong water spray. However, a number of contact insecticides approved for use against lace bugs can be used if necessary.
Life History and Habits: Lace bugs that feed on deciduous woody ornamental plants often overwinter as adults in bark fissures, branch crotches, or other safe areas. As the leaves unfold, the overwintering adults emerge and lay their eggs on the lower leaf surface. In a few days (May), the eggs will hatch, and the nymphs will feed on the undersides of leaves.
Depending on the type of lace insect, one to three generations are generated each year in Pennsylvania. The number of generations is also affected by the duration of the growing season. From egg to adult, development can take anything from 26 to 49 days. Lace bugs can be seen at various stages of development on deciduous woody ornamental plants until August or September.